VITAMIN NUTRITION OF THE STAPHYLOCOCCI WITH SPECIAL REFERENCE TO THEIR BIOTIN REQUIREMENTS

Abstract

The vitamin requirements of 90 coagulase-positive and 46 coagulase-negative staphylococci were studied in a casein hydrolysate medium. All of the coagulase-positive strains grow well when thiamine and nicotinic acid are the only added vitamins. However, 4 of these strains are stimulated markedly by pantothenic acid, and many of them are stimulated moderately by biotin. In contrast, 38 of the coagulase-negative strains have an absolute requirement for biotin, and the other 8 attain only 50-60% of maximum growth in the absence of biotin. In addition, 12 coagulase-negative strains require pantothenic acid for growth, and 2 of these also require pyridoxine. Avidin, in the form of 0.3% raw egg white, sharply inhibits growth of a coagulase-negative strain in the presence of 10 mug of biotin per 10 ml. Increasing the quantity of egg white in increments up to 5% gradually reverses the inhibition. Similar results were obtained in the presence of 2 mug of biotin, but in the presence of 20 mug of biotin no inhibitory effect of raw egg white was demonstrated. Biocytin replaces biotin on an equimolar basis for all 18 coagulase-negative strains tested. Tween 80 replaces biotin for 16 of 17 coagulase-negative strains studied. High levels of desthiobiotin or homo-biotin also replace biotin for 16 of 17 coagulase-negative strains. One coagulase-negative strain requires approximately 100 times as much biotin for growth as that required by other strains. This strain has a correspondingly high requirement for biocytin, homobiotin, or desthiobiotin.